Process of converting iron castings into steel or malleable iron.



UNITED sirivrEs PATENT OFFICE.

MARY AUGUSTA HUNTER, or PHILADELPHIA, PENNSYLVANIA. PROCESS OF CONVERTiNG IRON CASTlNGS tNTO'STE EL 0R winners, m'ou.

Specification of Letters Patent.

Patented. March 5, 1907.

Application filed March 28, 1906. Serialiloi 308,57 6.

invention are to convert rust-iron as quickly and as cheaply as possible without remelting into a stee capa same as higli grade tool-steel, further objects being to eliminate the suffocating fun'ies 1 which have hithertobeen prevalent in former processes of this nature and to obtain a resulting product which shall possess little, if

scale on the surface thereof; and it consists, essentia'll of subjecting the iron when heated to a o'nt slightly short of melting to the action ,0 sulfuric acid in gaseous or liquid form, thervarious steps of the process being hereinafter described in detail.

In carrying out the process I firstplace the cast-iron, which may be in the form of cast ings, bars, or blocks, into a suitable mulllefurnace or other receptacle, in which it may be heated to a high temperature.

\Vhilc not limiting my process to any particular type of furnace, l iind it can be used with particular advantage in the furnace which is covered by the United States Patout No. 699,759, granted to J. A. Hunter on the 13th day. of May, 1902. In this furnace at special provision is made for earrying out a process analogous to this one. The iron in the furnace is then heated to a high tempera.- ture short of melting-point. l usually find that aternpcratln'e between 1,7 ()t)" and 1,800" Fahrenheit is suitable for the carrying out of my recess. After-the iron has been heated to tiis high temperature it is treated with sulfuric acid in the form of a vapor orspiay. It will be evident that. this sulfuric acid may be applied to the essential point being that the acid come in contact with the iron at the high temperature. I may, however, mention one or two ways in which they may be carriedont.

)le of being rolled, halinmered, or drawn like wrought-iron or lowcarbon steel and which can be tempered the the iron in-niany dillercnt ways,-

First, it might be carried out by the means shown and described in United States Patent No. (309,759, in which the acid is introduced in pans through openings in the mullle to the iron when the proper temperature has been obtained. The high temperature of the flirnace vaporizes the acid. and the fumes thereof rise up and come in contact with the iron castings or ingots.

Secondly, the acid might be introduced in the form of' a spray by compressed air. Apparatus for carrying out this method is quite well known to those familiar with the art and need not be here described.

'lhirdly, the sulfuric acid might previousl y be vaporized external] to the furnace and forced into the furnace y its own pressure. 4

The theoretical operation of iny-process as I at present conceive it is as follows: The

sulfuric-acid vapor coming in contact with the iron at a high temperature decomposes, giving off oxygen. The oxygen burning the impurities in the iron raises the temperature of the furnace still higher, causing a molecular change to take place in the structure of the iron, as well as the chemical change due to the burning of the impurities. ical change which takes place in the iron com.- prises a recrystallization in the structure'of the iron and a conversion of a portion of the carbon into carbon of a different formnamely, into the carbon of cementationand an elimination of part of the combined carbon; In this physical transformation the molecules of the iron thus become more or less granulated, and the carbon of cementation acts as a binder to join the granules more closely together. The tensile strength and ductility of the metal is thus greatly increased. I

By variation in the proportion of the acid introduced into the furnace the nature of the finished product may be varied, according as steel, malleable iron, or wrought-iron is de-. sired.

The metal which is produced by my process as hereinbel'orc described possesses the peculiar properties of being capable of being rolled, hammered, and drawn equally well as ordinary wrought-iron or low-carbon steel and at the same time can be tempered equally well as higlegrade tool-steel.

The physto a point slightly short of the melting-point l The method of heating the iron or the of the iron; thenintroducing into the charnmethod of introducing the acid to the iron do ber sulfuric acid unmixed with any other renot form essential features of my process, ducing agent and continuing the heating, efand it is manifest that these can be carried fecting the decomposition the sulfuric acid out in a great Variety of different Ways, the and enabling the oxygen therein to act on the main feature being the application of the acid iron substantially as dcscril'lcd. to the iron at a high temperature. Signed at Philadelphia, Pmmsylvania, this What I claim as my invention is 23d day of March, 1906. v The mode herein described of converting MARY AUGUtfi'lA HUNTER. cast-iron into steel or malleable iron consistg Witnesses:

ing in heating the iron in a closed chan'iber, I. THOS. H. hiijAGINNlSS,

v A B. PECK. 

